Die and wire bonding is the most common interconnect technology employed in the electronic packaging industry. In recent years, new packaging trends have led to, for example, increases in the number of interconnections, circuit miniaturization, increased speed of assembly, reduced cost per interconnection and the like.
It should be noted that interconnection quality affects the quality of an end product. As the number of interconnections increases, the probability of producing a defective component also increases. Given that die and wire bonding typically occurs at a downstream stage of a semiconductor production process, the cost of a defective product due to a bad interconnect is high relative to a defective product which is detected at an early stage of the production process. It is currently possible to measure a height of bonded wires. This is also known as loop height. It is also possible to carry out inspection for the quality of the die/wire bonding as well as the integrity of die/wire/substrate after the bonding process.
Typical inspection methods for wire bonding (especially in the wire profile area) are usually carried out either manually (for example, visual check with a microscope, contact inspection and the like) or in a semi-automated manner. Such inspection methods are unfortunately slow, labour intensive, costly, and also prone to suffer physical damage due to contact and/or electrostatic damage. Moreover, manual inspection methods (for example, visual inspection with/without use of a sensor) are flawed due to human limitations, and are highly subjective and dependent on a human inspector.
Hence, there is clearly a need for improvements pertaining to inspection methods for wire bonding.